Conventionally, plastic materials derived from limited resource petroleum have been widely used; however, in the recent years, techniques with less burdens on the environment have been spotlighted. In view of the technical background, materials using cellulose fibers, which are biomass existing in large amounts in nature have been remarked.
For example, Patent Publication 1 discloses cellulose nanofibers having an average degree of polymerization of 600 or more and 30,000 or less, an aspect ratio of from 20 to 10,000, and an average diameter of from 1 to 800 nm as cellulose nanofibers having excellent reinforcing effects, characterized in that the cellulose nanofibers have crystal peaks of Iβ form in X-ray diffraction patterns. The resin composition containing the cellulose nanofibers shows excellent moldability and a coefficient of linear thermal expansion.
Patent Publication 2 discloses that pulps containing a lignin are subjected to a mechanical defibriation treatment to provide microfibrillated vegetable fibers with a structure coated with hemicellulose and lignin in that order, thereby making them easier to handle in an aqueous system, and that the fiber-reinforced resin blended with the vegetable fibers has a decomposition temperature higher than a conventional microfibrillated cellulose, so that they are excellent in thermal stability.
Patent Publication 3 discloses cellulose microfibrils having a modified surface, characterized in that a hydroxyl functional group existing on a surface of the microfibrils is etherified with at least one of an organic compound capable of reacting with the hydroxyl functional group, wherein the degree of substitution of surface (DSS) during etherification is at least 0.05. The publication describes that an elastomeric composition containing the microfibrils shows excellent mechanical strength.
Patent Publication 4 discloses a composite material containing cellulose microfibers of which surface is replaced with an ether group having a degree of substitution of surface (DSS) of at least 0.05.
Patent Publication 1: Japanese Patent Laid-Open No. 2011-184816
Patent Publication 2: Japanese Patent Laid-Open No. 2009-19200
Patent Publication 3: Japanese Unexamined Patent Publication No. 2002-524618
Patent Publication 4: FR2800378 Publication